Imagine plucking your own beans, strawberries, and tomatoes from the wall outside your kitchen door from a vertical garden that could fit into the tiniest balcony space but that would provide fresh crops all year round. And without a lot of effort from you. All you would have to do is plant in your modular wall, turn on the automatic watering and feeding system, then stand back and watch the plants grow. No soil, no watering, just fresh food every day of the year. Now imagine whole city apartment towers clothed with these sleek mounted panels, all providing fresh food right in the heart of cities from Dubai to New York. No longer gray and sterile, city skyscapes would be filled with towers of tumbling, green, modern-day Hanging Gardens of Babylon. This scenario may not yet be a reality, but one thing is for sure: the future of food production is looking up.
If climate change and population growth continue at their present levels, scientists claim that farming as we know it will no longer exist within 50 years. Fifty percent of the world is now urbanized—by 2050 that figure will have risen to 80 percent. And as the global population grows, available agricultural land is shrinking. In 1970 there was roughly one acre of farmland available for each person in the world, but by 2000 it had reduced to half an acre. By 2050 the United Nations predicts that it will drop to a third of an acre per person. How, quite simply, are we going to feed everybody?
For some, the answer could be vertical farms—vast steel towers in the heart of cities growing fruit and vegetable crops hydroponically (that is, using chemical nutrients rather than traditional soil). Rather than having to transport crops into the cities, which uses up valuable fuel and resources, why not grow them right there in the metropolis? A 30-story building covering a full city block (about five acres) could feed 50,000 people a year, according to the author of The Vertical Farm, Dickson Despommier, a professor at Columbia University. This is the world of agritecture: buildings designed to produce food on a mass scale. Images of how these towers might look are seductive—the transparent walls needed to let light in for growing crops making them look like futuristic hanging gardens—yet up to this point the costs of building them have been prohibitive.
Perhaps more realistic are the urban food-growing ideas of aerospace engineer and New York University professor Natalie Jeremijenko, whose bug-like pods are designed to perch on the roofs of skyscrapers. With their splayed stilt legs that would spread weight onto the loadbearing walls and a streamlined shape that would not only maximize sun exposure but minimize wind resistance, these greenhouses could sit on any unoccupied city rooftop, packed with crops growing in soil-free hydroponic trays.
Say goodbye to soil?
Hydroponics is the cultivation of plants in a nutrient solution rather than in soil. Plants are rooted into a lightweight, inert medium such as mineral wool, and then fed and watered with a nutrient solution. Productivity is greatly increased when crops are grown this way (from double to ten times the quantity of crops produced conventionally) and waste materials can be recycled. Hydroponic cultivation uses at least 20 percent less water than conventional growing, and there are no soil-borne pests and diseases to contend with, either.
Hydroponics are already transforming city rooftops. In 2010, Gotham Greens began planting rooftop farms in Queens and Brooklyn, in New York, growing greens and herbs hydroponically in greenhouses using renewable energy and captured rainwater. They sell their produce to the natural and organic grocery chain Whole Foods, which has branches across the city. The educational organization New York Sun Works projects that hydroponic farms spread over New York’s 14,000 acres of unshaded rooftop could feed as many as 20 million people a year.
But how do these futuristic projections affect the domestic balcony or rooftop gardener? Put simply, there may come a time in the not too distant future when city apartment buildings might be covered in crops, growing out from the sides of buildings and feeding the inhabitants within. On a more domestic scale, each apartment could come with its own edible wall on the balcony or even inside the building.
A potential glimpse into the future can be found in Shoreditch, east London, where a 6 × 13 ft. wall brims with greens and herbs, providing customers of the Waterhouse Restaurant with both a wonderfully modern and vibrant backdrop and a delicious lunch. Supplied by Biotecture UK, a leading designer of green walls, the wall combines frilly lettuces, spinach, arugula, and parsley that grow tantalizingly within reach, and cover the modular framework in a beautiful map of purples and greens. The edible walls are made up of modules filled with mineral wool, through which plug plants are pushed and into which they root. They are then fed and watered hydroponically.
The possibilities for such a system for domestic roofs and balconies are enormous, and Biotecture UK is now working on a small-scale, cost-effective model. The company’s designer, Mark Laurence, believes this technology would be particularly effective in the developing world. As it is more energy-efficient than traditional growing, the potential for such a technology to feed people in cities is enormous.
Laurence is currently adapting the company’s Biowall so that it can grow vegetable and fruit plants such as zucchini, bush beans, and tomatoes, working on its sustainability by making it easier to recycle the growing medium. He envisions a time not so far ahead when people living in cities could have their own personal edible wall on their balcony. They could receive pre-grown seedlings in the mail to plant and would then need to fill a water tank every so often that would trickle water and nutrients down to the plants’ roots. Once the vegetables had been harvested, the rockwool blocks they grew in could be taken to an urban recycling center to be replaced by fresh ones. It’s a simple solution, one with no electricity required, no daily watering hassle, and no heavy potting mix to carry up several stories.
And to those critics of hydroponics who say it is environmentally unsound because the feeds are non-organic, Mark says: “There’s no reason why you couldn’t use wormery feed, comfrey, or seaweed.”
The Urb Garden, designed by Xavier Callaud, incorporates just such an idea. In this cabinet-sized edible wall, the perfect size for a small domestic balcony, strawberries, tomatoes, greens, and herbs grow in traditional garden compost rather than hydroponic material, but they are fed by an integral wormery into which you add your kitchen scraps. A foot pump takes the feed and water up to the top of the wall where it drips down, and after each crop compost can be replaced using fertile worm casts—a beautifully sustainable system.
Callaud’s idea is currently a prototype, but it’s only a question of time before this product, and others like it, take the urban growing-your-own revolution that exciting step further. The next few decades will be crunch time for urban food production. There’s no doubt that cities will have to adapt to produce crops to help feed the world’s growing population, but whether they’ll be doing it in bug-shaped pods on the roof, up the sides of vast skyscrapers or in domestic-scale panels outside every apartment owner’s kitchen window, only time will tell. One thing is for certain: the urban landscape will look very different in 50 years time. And who knows, it might even be a little bit greener.